Reproduction with localized corrections



H. E. J. NEUGEBAUER 2,799,722 REPRODUCTION WITH LOCALIZEO CORRECTIONSJuly 16, 1957 Filed April 26, 1954 6 Sheets-Sheet l ,I Hl E. J :o: HA IJ1: O b Mn. Im: u: 1 s Mw A. o: 19| 9 LUII. im; ,CE m; li-.. Il l 4.7li.- Lf Lf n1 :i ,Ii

July 16, 1957 H. E. J. NEUGEBAUER. I 2,799,722

REPRODUCTION WITH LOCALIZED CORRECTIONSl l Filed April 26, 19.54 v 6SheetS-Sheei*I 2 July 16, 1957 H. E. J. NEUGEBAUER REPRODUCTION wTTRLOOALTZEO CORRECTIONS @sheets-sheet :s

Filed April 2,6, 1954 F mx h m .Il .nl o

"A A, T

MT h .l D C my.. u

uw Au A T2 TH To F), V)

' July 16, 1957 H. E. J. NEUGEBAUER v 2,799,722

` REPRoDUcTxoN 'WITH LOCALIZED CORRECTIONS Filed April 26, 1954 6Sheets-Sheet 4 From 9 From 6) 6u lll To lll-,14214 14 July 16, 1957 H.E. J. NEUGEBAUER 2,799,722

REPRODUCTION wim LOCALIZED CORRECTIONS Filed April 2 6, 1954 esheets-sheet 5 IL "nT w j\ 1w i;

1'; n' la'f la" im il lc l TO 14- *row To 14" Ta 14'" lrwwtor July 16,1957 H. E. J. NEUGEBAUER 2,799,722

REPRODUCTION WITH lI .OCLIZED CORRECTIONS 6 Sheets-Sheet 6 Filed April26, 1954 lrwzntor 2%, /7/ Attorneys United States Patent C signor toAdalia Limited, Montreal, Quebec, Canada, a corporation of CanadaApplication April 26,` 1954, Serial No. 425,567

Claims. (Cl. 17H-5.2)

Thisinvention relates to. a method and apparatus formaking,'reproductionsy with. corrections to sectional areas ofv thepicture which may be inaddition to but dierent from overall correctionsto the picture.

It. is .necessary that corrected color separations be made Where acolored original is to be reproduced as the color mixture.l lawsgoverning the preparation of uncorrected separations are not the sameas'the color mixture. laws of the reproducing system. A number ofmethod-s and apparatuses for making these corrected color separationshave been developed, based on scanning the originalpicturea-nd:separating its spectral components to provide what may be calledtristimulus signals which are some function of the tristimulus values ofthe portion ofthev original being scanned. These tristimulusl signalsare directed. toy a computer which generates corrected signalsfor use incontrolling the recording means. One suitable method and apparatus forthis purpose is that' described in my copending application Serial'N-o.420,434, filed the lst day of April 1954.

A disadvantage of electrical methods andY apparatuses for makingcorrected color separations hitherto' developed isthatthey lack theiieXibil-ity of manual' methods in that there isV no convenient way ofmaking localized corrections to sectional' areas of the picture.Thisdefect gives riseto problemswhere for example the initial trialprints are satisfactory except for the reproduction of the color in4 onearea, say the skin area of a person pictured. in. theV original. Itwillbe dit-heult and time consuming. to` attempt to remedy this byoverallcorrections,` as when.y the. particu-lar area in questionf has.been` corrected the' colors in other areas may then become distortedvand unsatisfactory. Localized corrections may also be de'- sirable toeffect deliberate deviations from the colors of the original. Thusit maybedesirable.. to make localized colorcorrections where Ythe color in a`particular area has fadedror is unsatisfactory for artistic reasons. ForeroV ample, color corrections to localized areas may be de-v sirable toharmonize the reproductions of several differenti pictures to be printedon' the samev page;

The object of this invention is to provideV a method andl apparatuswhich can. conveniently be used asv part of an electrical method orapparatus for producing corrected coljor separations with localizedcorrections to sectional areas. Although the main object ofthe inventionis the' provision of localized corrections forl the reproduction ofcolored originalsit iscontemplated that the. method and apparatus ofthis invention will also be suitable for making'y localized densitycorrections to monochrome pictures.

The general principle of this invention isV that a mask is providedhaving areas of a dilerential transmission, ratio in comparison to the.remainder of the mask. These areas of diilerential transmission ratio,correspondto the. areas of the original which are to receive localizedcorrections. The mask is scanned synchronously with the o ri'gnalandycontrol signals are generatedcorresponding to the transmission ratio ofthe portion of the mask "2,799,722 Patented July 16, 1957 ice scanned.These control means are used to control a switching means which brings aprecomputing means into the electrical circuit to give the desired`corrections for localized areas when the areas of the mask ofdiierential transmissiony are being scanned.y The switching means causesthe' precomputing means to be by-passed when areas other than thelocalized areas of themask are being scanned. Where colored pictures arebeing scanned there will be a computing means to which the tristimulussignals are normally fed to give overall color corrections for thesignalssupplied tothey recording means. For the special corrections tolocalized areas the precomputing means can conveniently be included` inthe` circuit which feeds the tristimulus signals to the computing meansso that the precomputing means will changel the input signalsfto thecomputer forthe localized areas. Alternatively,- the precom-putingmeanscan be loca-ted` so that it acts on the output signals from thecomputer. As a further alternative a separate circuit can be used forthe localized areas so that the precomputer imparts both the overallcorrections and the special corrections. Where density corrections arebeing made to a monochrome it may be possible toomit the computer anduse only the precomputer. Where different corrections are to be appliedto different localized areas the mask can have a diierent transmissionratio and a separate'. precomputer can be providedfor each localizedarea.

In accordancewith a preferredl embodiment of this in vention` provisionis made for the use of approximate masks in'- whichthe areas ofdifferential transmission ratio are larger than are approximatelycontoured totV the shapeof the localized areas of the original. The usevof approximate masks' greatly reduces the time requiredA to make themasks and also eliminates the effectV of minor maladjustments in thepositioning of the mask and. origi-r nal or in the synchronism of themeans for scanning` the mask` andithe means forscanning the original.Accurate` corrections are obtained with these approximate masks byincluding means within the switching means for including the precomputerin the circuit only when. not only is. an area of the mask ofdifferential transmission ratioV beingscannedbut also. when the.tristimulus signals each fall within afpredetermined range of values; inalmost every case this will give` a satisfactory resultas usually thetristimulus values of the areas of the` original immediately adjacent tothe area being corrected will have4 diierent. tristimulus values fromvthe area being cor` rected. Approximatemasks can, in many cases, beusedA for making density corrections toaV monochrome, but. there4 is agreater likelihood that the surrounding areas will have a similardensity to the area being correctedV than that these surroundingare'aswill have similar tristimulus values to the area beingcorrected; Insome: cases where colored reproductions are being made satis-A factoryresults" may be obtainable byl controlling.` the switching` meansenti-rely by the tristimulus signals but it ispreferredk that acombination of approximatel masks' and the'tristimulus signals be usedto control the switching; means.

In the drawings which illustrate the embodimentsof this invention:

Figure'l l is aI circuit diagram in block form illustratingv the.preferred embodiment of this invention;

Figure-22 shows an original picture to', be. reproduced;

Figure 2a showsfoneform of mask. for use in making: localizedcorrections to Figure y2;

Figure 2bshowsa-second form of mask for use" in making localizedvcorrections to Figure 2; A

liigurev 3 is a detailed view of'v the switch. bornand` switches;`

Figure, 4 is a detailed'. view; off4 a m'odied circuitr for: the;`switch`v box. shown in-ligurey 3;"

Figure 5 shows a modified circuit as an alternative to part of thecircuit shown in Figure l;

Figure 6 shows a further alternative to part of the circuit shown inFigure 1;

Figure 7 shows an alternative to the switching device shown in Figure 3Figure 8 is a detailed elevation view of diaphragm 53;

Figure 9 is a detail elevation View of diaphragm 66;

Figure l() shows a modification of part of Figure 7.

In the drawings which illustrate the preferred embodiment of thisinvention and in which similar numerals designate similar parts, Figurel shows a circuit diagram illustrating the method and apparatus inaccordance with the preferred embodiment of the invention; Figure 2shows an original to be reproduced; Figure 2a shows one form of mask foruse in association with the apparatus in Figure 1; Figure 2b showsanother form of mask. it may be assumed, for example, that in theoriginal picture 1 shown in Figure 2 that the skin of the Woman is toopale, the arms and hands 1a needing more yellow and magenta, the face 1bneeding more yellow and slightly more magenta. In addition the blue 1cof the Flowers may be too dull, a purer and brighter blue would bedesirable. The rest of the picture may be assumed to be satisfactory.

An electronic scanner for obtaining such corrected separations that thedesired changes of the colors of arms, face and flowers are producedautomatically is represented in Figure 1. Original 1 is scanned by meansof light source 4 and three photo electric cells 5, 5', 5 picking uplight reflected from the illuminated point of the original. Otherscanning methods may be used. The spec tral response curves of the photocells'S, 5 and 5 multiplied by the spectral transmission curves of colorfilters 5a, 5a and 5a which may be arranged between the original and thephoto cells are such that the signals b, g, r generated by the cells aretrichromatic coordinates of the color of the original. Their relation tothe tristimulus values of the original has been explained in mycopending patent application Serial No. 420,434. Sig nals b, g, r whichwill be referred to for brevityl as tristimulus signals are preamplifiedby amplifiers 6, 6', 6" respectively.

Signals m, j, c, n generated by the computing means subsequently to bedescribed and having a predetermined relationship to signals b, g, r arefed into recorders 14, 14', 14, 14 which produce by known methods fourcorrected color separations on sheet material 15, 15, 15"' or threecorrected separations where no black printer is included. Thedesignation corrected color separation means that these separations,when processed by a standardized method, yield printed multicolorpictures which are faithful reproductions of the original except forsuch color distortions as are an unavoidable consequence of the limitedcolor gamut of the printing inks, and. except for those areas (skin andflowers in the example of Figure 2) where deviations from the originalcolor are dcsired.

When signals b, g, r are fed into the four computers 13, 13', 13", 13"',these computers yield signals m, j, c, n,

which are used for controlling recorders 14, 14', 14, 14l` respectively,such that the separations 15 lead to faithful reproductions of original1 within the limits of the color gamut of printing inks. When neither apoint of the skin nor of the flowers is being scanned, preamplifiers 6,6', 6 are directly connected to computers 13, 13', 13, 13".

A mask Figure 2a is scanned synchronously with original 1. The scanningis synchronized by synchronizing means 3 controlling light sources 4 and7. The transmission ratio of the mask is different from the remainder ofthe mask at areas corresponding to such areas of the original in whichlocalized color changes are desired. For instance, the mask 2' Figure 2acan have an overall transmission ratio substantially equal to unity. Itstransmission ratio can be substantially zero at the areas 2ccorresponding to the flowers...it-canibe about atthe areas 2acorresponding to the arms, and be about 70% at the areas Zbcorresponding to the face.

Mask 2 lis scanned by means of light source 7 and photo electric cell S.Signals generated by the photo cell are preamplified by amplifier 9 andfed into a switch box 10.

Switches 12a, 12a', 12d" are controlled by switch box 10 in such a waythat switches 12a, 12a', 12a", 12b, 12C, 12C are open and switches 12d,12d', 12d are closed when photo cell 8 receives maximum light. In thisstate of the switches preamplifiers 6, 6', 6 are connected to computers13, .`13". The preampliers are also connected to precomputers 11a, 11a',11's". However, as long as switches 12a, 12C" are open the precomputersare disconnected from Ycomputers 13, 131i?.

When the intensity of light falling on photo cell 8 is reduced to about70% of its maximum value, switch box 1t) transmits signals to theswitches so that only switches 12a, 12a', 12a" are closed while theother switches 12b 12C" remain open and switches 12d, 12d', 12d" areopened. Preampliers 6, 6', 6" and precomputers 11b, 11b', 11b", 11C,11e', 11C" are thus disconnected from computers 13, 13".

Precomputers 11a, 11a', 11a produce signals b', g', r'

which are fed into computers 13, 13" instead ofk b, g, r respectively.Signals b', g', r are the trichromatic coordinates of such colors as theface should have to give a pleasant picture. Precomputers 11a, 11a',11a" are adjusted to give the desired effect on the basis of experienceor trial experimentation.

If photo cell 8 receives only 30% of the maximum light switch box 10sends out signals which close switches 12b, 12b', 12b While all theother switches remain open or are opened. In this case signals b, g", r"generated by precomputers 11b, 11b', 11b" are fed into computer 13, 13"instead of b, g, r. They are the trichromatic coordinates of the colorsof hands and arms which Will theV owers.

give a pleasant picture.

If, photo cell S receives no light, precomputers 11e,l

11C', 11C" are similarly connected by switches 12C, 12', 12 to computers13, 13". Precomputers 11C, 11C', 11e" provide signals b", g", r" whichare the trichromatic coordinates of the desired blue of the flowers.

A photographic method can be used to facilitate making the mask. Aphotographic negative of original 1 is made and all the sections of thepicture which are to be clear on the mask, are covered with a protectivelayer which is impermeable to light. The uncovered areas are bleached ina silver solvent and the areas corresponding to the hands and the facecovered by pieces of thin material of the appropriate transmissionratios. A photographic print of this negative constitutes the mask.

Since, quite often, the contours of the areas which need specialcorrections, are difficult to follow with the brush, the method can bealtered so that the simplified mask of Figure 2b can be used. Toaccomplish this, the action of switch box 10 is controlled not only bysignals from photo cell 8 but also by signals b, g, r.

Under the assumption that the trichrornatic coordinates of the `blueflowers, as they are represented on the original, lie between the limitsBf and Bf', Gf and Gr', Rf and Rf' the switch box is adjusted in such away that switches 12C, 12e', 12C" are closed when Since it could happenthat a color with trichromatic coordinates between the same limitsoccurs also in other sections of the picture, for instance in the womansfrock, the switches 12e, 12e', 12C are closed only when, at the sametime, photo cell 8 receives no light. Therefore, a mask is still usuallyneeded, but its contours can be very inaccurate as can be seen fromFigure 2b, in which 2"a represent the areas of the mask for correctingthe hands, 2b the areas for the face and 2c the areas for v A suitableconstruction for` switch box and switches 12d, 12b, 12e, 12a? is shownin` Figure-3. In Figure 3 voltage supplied` by preamplifier 6' andproportional to signal b isn applied t'o potentiometers 21a, 21h', 21e.In the same way voltages proportional'to g and r are applied to sixpoteutiometers 22a, Y. 23e. Potentiometers 21a, 22a, 23a will lirst beconsidered; Two relays 2411 and 24a are arranged in parallel toparts ofthe resistor 21a,rand theA variable contacts of the potentiometer areadjusted so that tlie contact of relay 24a is actuated when voltage brises over, or drops under the value Bs, while the contact of relay 24ais actuated when voltage b rises over, or dropsunder, the-value' Bs. By'an initial measurement the. values Br andl VBt' have been determined aslower and upper limits of bk when tlie trichromatic coordinates ofthecolor of skin as represented on originall 1 are measured.4 Thevcorresponding limits for g and r may be' Gs, Gs', RsuRs'. The variablecontacts of potentiometers 22a" and 23a are adjusted in' such a way thatthe contacts' of relays 25a, 25a', 26a, 26a are actuated` when signal gpasses the values Gs or Gs' or signal r the" values Rs or Rsrespectively.

The contacts et said six relays are arranged@ in series. The contacts ofFigure 3 are drawn under the assumptionthat signals b, g, r`l liebetween the limiting values Bg, Bs; Gs, Gs'; Rs, Rs ev., that all area.ot the picture representing skin is being scanned. Contacts 24a, 25a,26a are open, contacts 24a', 25a', 26a' are closed when no current istiowing, Therefore, when skin is being scanned, all the six contactsareiclosed.

Since, on original 1, the womans Atace' and arms are represented by thesame color, but different corrections are desired, potentiometers'`211:', 225, 23b are" adjusted in suchv a way thatrelays- 2'4b, 26h' areactuated at theY same values of b, g, r as relays 24a-,1. 26a. By meansof mask 2 relays 24a to 26a will be used in the correction of the colorof the face, relays. 24h to 26h will be used in correcting the color ofthe arms.

Contacts' 24e toA26c are used in correcting- Vthe color of the flowers;Consequently thecontacts of potentiometers` 21e, 22e, 23e are adjustedsuch that the contacts of relays, 24C to 26c'are actuated at the valuesBf and Br for b, Gf and Gr for g, Rf and Rr for 1'.

The manner in which the mask is used to control the operations will nowbe described. A` resistor 2 7 is connected to preamplifier 9. Relays28.42, 29a, 28b,y 29b, 29e are connected in parallelto sections ofresistor 27 inY such a way that 29a is operated when the transmissionratio of the mask drops below, for example, 85%; 28a and 29h areoperated when it drops below 50%, and 285' and 29C are operated when itdrops below 15%. Contacts 28a and 29a are arranged in series withcontcts 24a to 26u. Contact-s 28b and 29b are. in series with contacts24b to` 2Gb'. Contact 29e is inv series with contacts 24e to 26o'.

At the moment when the womans face is being scanned, the voltage appliedto resistor 27 will be 70% of its maximum value. Therefore contactsy28a` and 29a are closed, but contacts 29b and 29C are open. Constant D.C'. voltages are applied to the terminals 30a, 30b, 30C, therefore a'current is flowing in the circuit with the terminals 30a, but no currentis owing in the two other cCit'S'.

If the womans arms are being scanned all twelve conta'cts 24a to 26a and24'b to 26h' are' closed as shown in Figure 3. But the voltage' appliedto resistor 27 is `only 30% of its maximum. Therefore contacts 28a and29C are open, while contacts Zeb and 29b closed. Only the circuit withthe `terminals 3017' is carrying current. lf finally the ilo'wers areVbeing scanned the contacts 24e to'ic and contact 29e areclosed while 28hand 28a are op'e'. In this case only the circuit with terminals 30ecarries current.A v

Switches 12a, 12b and 12C containing relays are cond nected so that'their relays are actuatedr by the circuits containing` contacts- 29a,29h and 29e respectively and switch 12d also containingv relays isconnected so that its-relays: will be actuated by all three circuits. Itshould be mentioned that none' ofthe three circuits carries cur-` rentwhen a clear part of the mask is being scanned-` be cause then thelthree contacts 29a, 291;, 29's` arel open. Consequently the six contactsof switch 12d' are closed, whereas those of switches 12a, 12b, 12o areopen'. When either the face, or the arms, or the owers are beingscanned, either the contacts of switch 1221 or of switch 12b or ofswitch 12b, respectively are closed while one pair of the contacts ofswitch 12d is open.

Switches 12a' 12d are similarly connected in parallel to the fourswitches'l 12av to 12d asV shownV i-n Figure l.

In Figure 3' all the relayshave been illustrated as being of theelectro-mechanical type. It will be apparent that they can be replacedby tubes for fast working scanners. Each relay can for instance bereplaced by the nip-nop shown in Figure 7 which will'` be explainedbelow.

If a picture contains only two areas needing special correctionsditerent from the rest of the picture, then two transmission ratios ofthe mask, for instance 30% and 70% but not zero, are used and thepotentiometers 21a, 22a, 23a,.21b, 2`2b, 23h are adjustedto their cor,-responding limiting. values as explained before.

If apict'ure contains more than three areas. needing special correctionsthe same principle as shown in Figure 3 can be extended to four, five,or six special corrections.

Another possibility where two or more areas require ditterentcorrections is t use the same transmission ratio for the portions of themask corresponding to these areas and to rely on thev tristimulussignals to differentiate between the areas.

Where accurate masks as shown in Figure 2a are used the circuit shown inFigure 3 can be simplified to omit the provision for controlli-ng theswitches by means of the tristimulus signals. The simplified circuit isshown in Figure 4 the elements of which bear the same designations andoperate in a similar manner to the corre-v spending elements in Figure3.

Computers 13 and precomputers 11 may conveniently be of the typedescribed in my copending application Serial No. 420,434 but othercomputers can be used as substitutes.

Figure 5 shows a different arrangement where alter native computers areused instead of precomputers. Four computers 31, 31, 31", 31 areadjusted so that each of them supplies a different quadruplet of signalsm, j, c, n when the same triplet of signals b, g, r is fed into them.Switches- 12ml, 12n" are operated by signals from switch box 10 so thatonly one of the computers 31 to 31 is connected to the lines designatedm, j, c, n, and leading to the recorders 14 to 14 of Figure l. Switchbox 10 may be controlled by signals from the mask or by signals frommask and original or uncorrected separations. In the latter two casesthe connections shown by dotted lines 3419', 34g, 34r in Figure 5' arecompleted.

In many cases the special corrections desired in restricted areas of thepicture can be effected at asuicient accuracy by such simpletransformations as where P', Q', U are properly chosen constants. Inthis case the computer arrangement can be simplied considera'bly' asshown in Figure 6. i

Three variable gain ampliiers 32, 32', 32" are inserted in the pathsfrom preampliiers 6, 6', 6" to computers 13 to 13". If the gain of theamplifiers is adjusted to one specified value,y for instance 100, thenthe signals m, j, c, n supplied by computers 13 to 13" may bethose'leading to a faithful reproduction within the gamut of printinginks. The gainv can be varied by changing the grid voltage oftheamplifier tubes 32, 32', 32". For this purpose potentiometers, 33a,33d,- fed by a constant D. C. voltage can be adjusted so that diiferentgains are obtained according to the state of switches 12a, 12d.

If, for instance, switches 12a, 12a', 12a" are closed and the otherswitches 12b to 12d are open then the gain of amplifiers 32, 32', 32" iscontrolled by potentiometers 33a, 33a', 33a". It may be assumed as amatter of example that these potentiometers are adjusted such that thegain is 100.

If switches 12b, 12b', 12b" are closed and the other switches are openthen the potentiometers 33h, 3311', 33h" are controlling the gain. Theymay be adjusted so that the gains of the amplifiers 32, 32', 32" arerespectively lOOP', lOOQ', lOOU' In a similar manner potentiometers 33e,33C' 33d" are adjusted and used to produce different corrections.Switches 12a to 12d" and switch box 10 may be of the same type as shownin Figure 3 or Figure 4.

Figure 7 shows an example of an electronic switching device. Cr tubeswith magnetic detiection are preferable as switching means becauseditferent sections of the switching device and of the computers can bekept separate without conducting connections between them.

The beam of Cr tube 51 is deviated by currents which are proportional tosignals g and r. The screen of the tube is imaged by lens 52 ontodiaphragm 53 which has a rectangular aperture which can be adjusted insuch a way that light passes through the aperture when Gs g Gs' and RS1' RS'. Lens 54 images lens 52 onto photo cell 55. The voltage dropalong resistor 56, when the photo cell receives light, is used tocontrol the beam intensity of Cr tube 57. Voltage is applied betweengrid and cathode of tube 57 such that no beam leaves the gun when bothterminals of resistor 56 are at the same voltage. When photo cell Sreceives light the potential of the grid is shifted towards positivevalues so that an electron beam is produced. This beam is deviated bycurrents proportional to signals b and by signals from the mask. Thescreen is imaged by lens 58 onto diaphragm 59, lens 58 is imaged by lens60 onto photo cell 61. The rectangular aperture of diaphragm S9 isadjusted so that photo cell 61 receives light when BS b Bs and, at thesame time, the transmission ratio of the mask is about 70%.

Triode 64 is connected in parallel to resistor 62. The grid voltage issuch that an anode current is owing when there is no voltage dropbetween the terminals of resistor 62. When photo cell 62 receives lightthe grid voltage is shifted towards negative values so that the anodecurrent is interrupted. The switching voltage is produced between thepoints A+ and A- of resistor 63. When the womans face on the picture isbeing scanned the voltage drop between A+ and A- is Zero. When any otherpart of the picture is being scanned A- is negative with respect to A+.Y

In a corresponding manner two switching voltages are produced betweenthe terminals of resistors 63' and 63". Diaphragme 53', 59', 53", 59"are adjusted in such a way that points B+ and B- as well as C+ and C-are at the same potential except when either the womans arms (B3 b Bs',Gs g Gs', Rs r Rs, and transmission ratio of mask about or the flowersand transmission ratio of mask zero) are being scanned. When the armsare being scanned B- is negative with respect to` B+ and when theflowers are being scanned C- is negative with respect to C+. l

A fourth switching voltage is generated between terminals D+ and D- ofresistor 70. Grid and cathode of Cr tube 65 are connected to resistor63' in such a way that an electron beam leaves the gun when B+ ispositive with respect to B-, but that the electron beam is interruptedwhen B+ and B- are at the same voltage. The two deviation coils areconnected to resistors 63 and 63" respectively and a diaphragm 66 isarranged in front of the screen in such a way that light from the screenreaches photo cell 67 when A+ is positive with respect to A- and C+ ispositive with respect to C-. lt however, either A+ and A- or C+ and C-are at the same potential the electron beam changes its direction sothat the luminous spot of the screen is covered by diaphragm 66. Triode69 is connected to resistor 68 in such a way that resistor 70 is freefrom current while a current tiows through 68 and vice versa.

The lower half of Figure 7 shows the manner in which the switchingvoltages can be used to control four different computers to produce fourdifferent signals m, m', m, m" The computers may be of the memory typedescribed in my copending application Serial No. 429,434. Intelligencerecorded on lenticulated memory screen 71 is read by means of Cr tube 72and orthicon 73. Resistor 7i) is connected to grid and cathode of theorthicon in such a way that the latter works when D+ and D- are at thesame voltage, but is interrupted when D- is negative with respect to D+.In a similar way orthicons 73', 73" and '73" are connected to resistors63, 63', 63 respectively. The intelligence recorded on lenticulatedmemory screens 73', 73", '73" is different according to the desiredcorrections.

As is obvious from above descriptions and from Figure 7 only one of thefour orthicons is working at any moment and not the three otherorthicons. Ordinarily signals m are produced by orthicon 73. When thetace is being scanned orthicon 73' produces signals m', when the armsare being scanned orthicon 73" produces signals m, and when the flowersare being scanned orthicon 73" produces signals m Either signals m, m',m" or m" are transmitted to recorder 14 of Figure l.

lt may be noted that any one of the switching voltages is zero when thecorresponding orthicon is working. For example, A+ and A- are at thesame potential when orthicon 73 is working. Therefore, the intensity ofthe electron beam emitted by the gun of the orthicon is independent ofthe switching means. Special feed back systems can be used to keep theintensity of the electron beam constant while the orthicon is working.

The triodes 64, V64', 64" and 69 serve to secure this independence ofthe orthicons from the switching means. Such an independence could notbe obtained when the voltages at the terminals of resistors 62, 62', 62"and 68 were used for switching purposs because then a current would beowing through one of the resistors while the corresponding orthicon isworking. Current variations would cause intensity variations of theorthicon.

Additional sets of computers can be used to produce signals c, j, n, andthese can be connected in parallel to those shown in Figure 7, orthe'four corrected separations can be made in succession. In the lattercase no change to the lelectrical circuits are required, but the memoryscreens are replaced in turn by screens representing the correctedvalues of ic, j, n respectively.

In Figure 8 diaphragm 53 is shown in elevation view. The circleindicates the image of the screen of tube 51. Four angular holders havegrooves in which thin metal plates 81 and 81a are slidably mounted. Thesmall rectangle almost at the centre is the aperture of the diaphragm.Plate 81 is brought in such a position that its lower edge goes throughthe image of the luminous spot on tube 51 when g=Gs. The upper edge ofplate 81' is adjusted so that its upper edge passes through the image ofthe luminous spot when g=G's.

Correspondiugly plates 81a and 81a' `are adjusted so that their edgespass through the images of the luminous spot when either r=RS or r=Rs,leaving open between them the spaceR's-l-r-l-Rs.

Diaphragms 53', 53, 59, 59', 59 are alll ofthe same design. In the caseof diaphragm 59, for instance, plates 81 and 81 are adjusted so that theedges correspond to the values b=Bs and b=Bs respectively, and' plates81a and 81a are adjusted so that their edges leave'a space free betweenthem which corresponds to transmission coefficients of mask 2'" or 2"between the limiting values 50% and 85%. The pla-tes are similarlyadjusted' in the cases of the other diaphragms with obviousmodifications,

Figure 9 is an elevation view` of diaphragm 66.` The hatched area isimpermeable-to light.

Thatpart of Figure 7 within the dashed line can be used as switch box 10of Figure l or Figure 5. In this caseit is advisable to replacethemechanical relays 12a, 12b; 12e, 12d, 12a', a. s. o'. by electronictubes as, for instance, shown in Figure llO.

Pentode 85d serves to transmit or out off signals from preamplifier 6whoseI exit is connected to cathode and lirst grid of the pentode;Cathode and second grid are connected to points D+ and D- of'Figure 7'.TheV grid bias is adjusted in such. a way' that the tube transmits ananode current when- D+ and D- are at the same potential, and that theanode current is interrupted when D- is negative with respect to D+. Avoltage proportionalE to thev signals from preamplifier 6 is supplied atpoints D+ and D"- when D+ and D- are at the same potential. ThissectionY of: Figure- 10 can be used `as switch 12d. The pentodes 85a,857:, 85o are connected Vsimilarly to pentod'e 85d with obviousmodiiications as shown` in Figure l0, so that they will serve asswitches 12a, 12b, 12o.

From the foregoing explanations it is apparent that all: the mechanicalrelaysshown: in the figures and mentioned i'n this specification can bereplaced by electronic tubes'- toi ensure higher operational speed.

l claim:

li'. Arr` apparatus for making corrected color separations for use inmaking reproductions of'a colored kpicture with color corrections for atleast one sectional area of the picture differing from the overall colorcorrections, comprising means for scanning the picture and generatingelectric tristimulus signals-corresponding to the tristimulus values ofthev picture, means for scanning a mask having areas: with atransmission ratio differing from the transmissi'onratio of theremainderof the mask in synchronism with the scanning of the picture, said areasof the mask corresponding to the portions of the picture which are tohave color corrections differingv from the. overall color corrections,meansfor generating' sign nals corresponding to the transmission ratio`of the portion. of the mask being scanned, recording means forrecording; corrected. color separations computing means for generatinginputy signals for the. recording meanshaving overallcorrections,..precomputing meansr for generating additionallycorrectedsignals for said sectional'area, switching-means; controlled by saidsignals corresponding tofthetransmission: ratio ofthe. portion of themask being scannedl for: luy-passing. said precomputing means anddirecting the. tristimulus signals to the recording means through thercomputing means: when` areas, of the picture other than said at leastone sectional area are being scannedI andfor directing the tristimulussignals to the recording meansft-hrou'gh the. precomputing means and thecomputing means when said at least one sectional area is; being scanned:i

2. An apparatus for making corrected color separations for use inmakingV reproductions of a colored pic-l ture with color corrections forsectional areas of the picture differing from the overall colorcorrections and from each other, comprising means for scanning thepicture and generating electric tristimulus signals corresponding to thetristimulus values of the picture, means for scanning a mask havingareas with a transmission radiodiifering fromfthe' transmission lratio of the remainder of the mask, the transmission ratio differing between`each' area` in which a different color correction is to be made, thescanning of the mask' being in syn'- chronisrrr withthe'scanni'ng ofthepicture, said*A areas of the mask corresponding to the portions of thepicture which are to havev color corrections, means for generatingsignalsl corresponding to the transmission' ratio of the portion of themask being scanned, recordingy means for recording corrected colorseparations computing means for generating input signals for therecording means having overally corrections, a precomputing means foreach area in which a separate correction isl toI be made for generating'additionally corrected signals for the last mentioned area, switchingmeans controlled by said signals corresponding to the transmission ratioof the portion of the mask being scanned for by-passingsaidprecomputingy means and directing the tri'stimulussignals to therecordingd means' through the computing means when' areas of thelpicture other thanV saidl sectional areas are being scanned and fordirecting the tristimulus signals to the recording meansl through theprecomputing means for one-of the sectional areas and the computingmeanswhenI said" one ofthe sectional areasis being scannedi.

3. An apparatus for making reproductions ofr al picture with densitycorrections to at least one sectional area of the picture comprisingmeans for scanning the picture and generating' signals corresponding toyat least one spectral component of: the picture, means` for scanning amask havingareas with a transmission ratio' difiering from thetransmission ratio of" the remainderl of the mask in synchronism withthe scanning of the picture, saidy areas of the mask corresponding tothey portions of the picturev which are to have said density correctionsand being largerthan said portions soasv to have approximately similaroutlinesl to said portions, means for generatingl signals' correspondingtothe transmission ratio of the portion of the mask being scanned,recording means for're'cording said reproductions means for generatingcorrected signals" for saidl sectional area, switching means controlledlby said signals corresponding to at least one spectral component of theoriginal and by said signals corresponding to the transmissiony ratioof' the portion of the mask being' scanned forv directing signals to therecording means without said' corrections when areas offl theA picture'-other thanl saidV areasv of' the mask are being scanned? ory when saidsignals corresponding to at least one spectral component of" the pictureare Out*- side ay predetermined range off values and forv directingsignals' to the recording means; including said density correctionsjwhen said=y areas of the mask are being scannedandwhenalso*-saidsignal's corresponding tov at least' one spectral? component or' thepicture arey within 'said predetermined: range of values.

4;. An apparatus for makingV corrected" color separations foruse inmaking reproductions of a coloredy picture with' color corrections forVsectional areas of the picture differing from the overall colorcorrections and from eachother, comprisingmeans for scanning the pictureand generatingY electric trist-imulus signals cor-responding tothetristimulus values of the picture; means for scanning a-- mask havingareas with a transmission ratioy diitering from"` the transmission ratioof th'e'l remainder of the mask'- ini` synchronismv with the scanning ofthe picture, saidr areas of the mask corresponding to the portions offthe picture which are-to have saidl density corrections.- andbeinglarger thanA said portions so as'r4 to have` approximately similaroutlines to said" portions; means forf generating-1 signalslcorresponding to the' transmission ratio of the portion of the maskbeing scanned, recording means for recording corrected colorseparations, computing means for generating input signals for therecording means having overall corrections, a precomputing means foreach area in which a separate correction is to be made for generatingadditionally corrected' signals for the last mentioned area, switchingmeans controlled by said tristimulus signals and by said signalscorresponding to the transmission ratio of the portion of the mask beingscanned for by-passing said precomputing means and directing thetristimulus signals to the recording means through the computing meansvwhen areas of the mask are being scanned or when said tristimulussignals are outside a predetermined range of values and for directingthe tristimulus signals to the recording means through the precomputingmeans for one of the sectional areas and the computing means when saidareas of the mask are being scanned and when also said tristimulussignals are within said predetermined rangeof values.

5. An apparatus for making reproductions of a picture -with densitycorrections to at least one sectional area of the vpicture comprisingmeans for scanning the picture land generating uncorrectedr signalscorresponding to at least one spectral component of the picture, meansfor scanning la mask having areas with a transmission ratio differingfrom the transmission ratio of the remainder of the mask in synchronismwith the scanning of the picture, said areas of the mask correspondingto the portions of the picture which are to have said densitycorrections, means for generating signals corresponding to thetransmission ratio of the portion of the mask being scanned, recordingmeans for recording said reproductions, means controlled by said meansfor scanning the .picture for generating corrected signals for saidsectional area, switching means having means acting when in onelposition to direct only uncorrected signals corresponding to said atleast one spectral component of the picture to the recording means andacting when in a second position todirect only said corrected signals tothe recording means and said switching means including control meansactuated by said signals corresponding to the transmission ratio of theportion of the mask being scanned for adjusting said switching means tosaid one position when areas of the picture other than said at least onesectional area are being scanned and for adjusting said switching meansto said second position when said at least one sectional area of thepicture is being scanned,

6. An apparatus for making reproductions of a picture with densitycorrections for at least one sectional area o f the picture differingfrom the overall density corrections, comprising means for scanning apicture and generating signals corresponding to at least one spectralcomponent of the picture, means for scanning a mask having areas with `atransmission ratio differing from the transmission ratio of theremainder of the mask in synchronism with the scanning of the picture,said areas of the mask corresponding to the portions of the picturewhich are to have density corrections differing from the overall densitycorrections, means for generating signals corresponding to thetransmission ratio of the portion of the mask being scanned, recordingmeans for recording said reproductions, computing means for generatinginput signals for the recording means having overall corrections, meansadditional to said computing means for generating differently correctedsignals for said sectional area, said input signals and differentlycorrected signals being derived from the means for scanning a pictureand generating signals corresponding to at least one spectral componentof the picture, means for directing signals corresponding to said onespectral component of the picture'and corrected only by said computingmeans to the recording means, means for directing signals correspondingto said one spectral component of the picture and corrected both by saidcomputing means and by said means additional to the computing means tothe recording means, switching means having means acting when in oneposition to direct only said signals corrected only by the computingmeans to the recording means and acting when in a second position todirect only said sigynals corrected both by said computing means and bysaid means additional to the computing means to the recording means, andsaid switching means including control means actuated by said signalscorresponding to the transmission ratio of the portion of the mask beingscanned for adjusting said switching means to said one position whenareas of the picture other than said at least one sectional area arebeing scanned and for adjusting said switching means to said secondposition when said at least one sectional area of the picture is beingscanned.

7. An apparatus for making corrected'color separations for use in makingreproductions of a colored picture with color corrections for at leastone sectional area of the picture differing from the overall colorcorrections, comprising means for scanning the picture and generatingelectric tristimulus signals corresponding to the tristimulus values ofthe picture, means for scanning a mask having areas with a transmissionratio differing from the transmission ratio of the remainder of themaskv in synchronism with the scanning of the picture, said areas of themask corresponding to the portions of the picture which are to havecolor corrections differing from the overall color corrections, meansfor generating signals corresponding to the transmission ratio offtheportion of the mask being scanned, recording means for recordingcorrected color separations, coniputing means for generating inputsignals for the recordingmeans having overall corrections, meansadditional to said computing means for generating differently correctedsignals for said sectional area, said input signals and differentlycorrected signals being derived from the means for scanning a pictureand generating electric tristimulus signals corresponding tothetristimulus values of the picture, means `for directing said electrictristimulus signals corrected only by said computing means to therecording' means, means for directing said tristimulus signals correctedboth by`said computing means and by said means additional `to thecomputing means to the recording means, switching means having meansacting when in one position to direct only said tristimulus signalscorrected only by said computing means to the recording means and actingwhen in a second position to direct only said signals corrected both bysaid cornputing means and by said means additional to the computingmeans to the recording means, and said switching means including controlmeans actuated by said signals corresponding to the transmission ratioof the portion ofthe mask being scanned for adjusting said switchingmeans to said one position when areas of the picture other than saidareas of the picture which are to have color corrections differing fromthe overall color corrections are being scanned and for adjusting saidswitching means to said second position when the areas of the picturewhich are to have color'corrections differingV from the overall colorcorrectionspare being scanned.

References Cited in the le of this patent UNTTED sTATEs PATENTS2,413,706 Gunderson Jan. 7, 1947 2,434,561 Hardy Jan. 13, 1948 2,571,322Yelland Oct. 16, 1951

